The present invention is directed generally to power-return tape measures of the type commonly used to measure linear distances.
Modern tape measures (or “tape rules”) typically include a coiled tape that is spring-biased towards a retracted position. A housing generally surrounds and protects the tape and a retraction spring and includes an opening through which a distal end of the tape extends. Typically, the tape measure housing consists of two housing halves that are joined together by one or more screws. In addition, one of the housing halves typically includes an inwardly pointing integral post that provides an anchoring point for one end of the retraction spring. During use, the distal end of the tape is pulled away from the housing; when released, the retraction spring pulls the tape back into the housing so that the tape returns to the retracted position.
One important consideration when designing commercially available tape measures is that the tape measure should be able to function even after being repeatedly dropped, as frequently occurs on a construction site. Dropping the tape measure subjects the tape measure to substantial shock loadings that sometimes lead to the retraction spring becoming pinched or otherwise misaligned with respect to the anchoring post, quickly rendering the tape measure unusable. As such, it is becoming more common to anchor the post to the housing, such as by screwing the two together at both ends of the post.
The post typically includes a slot that is used to engage the retraction spring. Indeed, one approach to configuring the post is to have the slot extend all the way to one end of the post, so that the spring may be slid into engagement with post by inserting the spring into the slot from the “split” end of the post. Then, when installation is complete, the screw used to secure that end of the post to the housing also serves, in a way, to close off the slot so as to capture the spring in the slot. In addition, the tape measure's belt clip is sometimes attached to the housing using the same screw that secures the split end of the post. However, it has been found that securing the belt clip to the housing in this fashion sometimes leads to the screw being pulled out, particularly when the tape measure is being removed from its packaging by the consumer.
Accordingly, there remains a need for alternative tape measure designs, preferably designs that are more robust.